const express = require('express');
const router = express.Router();
const db = require('../../db');
const { hasRole } = require('../../middleware/authMiddleware');

// ==========================================
// 1. Asset Management
// ==========================================

// Get All Assets
router.get('/assets', async (req, res) => {
    try {
        const [rows] = await db.query('SELECT * FROM assets ORDER BY created_at DESC');
        res.json(rows);
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

// Get Asset by ID
router.get('/assets/:id', async (req, res) => {
    try {
        const [rows] = await db.query('SELECT * FROM assets WHERE id = ?', [req.params.id]);
        if (rows.length === 0) return res.status(404).json({ error: 'Asset not found' });
        res.json(rows[0]);
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

// Create Asset
router.post('/assets', async (req, res) => {
    const { id, name, category, model_name, serial_number, manufacturer, location, purchase_date, manager, status, specs, purchase_price, image_url } = req.body;

    try {
        const sql = `
            INSERT INTO assets (id, name, category, model_name, serial_number, manufacturer, location, purchase_date, manager, status, specs, purchase_price, image_url)
            VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
        `;
        await db.query(sql, [id, name, category, model_name, serial_number, manufacturer, location, purchase_date, manager, status, specs, purchase_price, image_url]);
        res.status(201).json({ message: 'Asset created', id });
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

// Update Asset
router.put('/assets/:id', async (req, res) => {
    const { name, category, model_name, serial_number, manufacturer, location, purchase_date, manager, status, specs, purchase_price, image_url } = req.body;

    try {
        const sql = `
            UPDATE assets 
            SET name=?, category=?, model_name=?, serial_number=?, manufacturer=?, location=?, purchase_date=?, manager=?, status=?, specs=?, purchase_price=?, image_url=?
            WHERE id=?
        `;
        const [result] = await db.query(sql, [name, category, model_name, serial_number, manufacturer, location, purchase_date, manager, status, specs, purchase_price, image_url, req.params.id]);

        if (result.affectedRows === 0) return res.status(404).json({ error: 'Asset not found' });
        res.json({ message: 'Asset updated' });
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

// ==========================================
// 2. Maintenance History
// ==========================================

// Get All Maintenance Records for an Asset
router.get('/assets/:asset_id/maintenance', async (req, res) => {
    try {
        const [rows] = await db.query('SELECT * FROM maintenance_history WHERE asset_id = ? ORDER BY maintenance_date DESC', [req.params.asset_id]);
        res.json(rows);
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

// Get Single Maintenance Record by ID
router.get('/maintenance/:id', async (req, res) => {
    try {
        const [rows] = await db.query('SELECT * FROM maintenance_history WHERE id = ?', [req.params.id]);
        if (rows.length === 0) return res.status(404).json({ error: 'Maintenance record not found' });

        const record = rows[0];

        // Fetch used parts
        const [parts] = await db.query(`
            SELECT mp.*, a.name as part_name, a.model_name 
            FROM maintenance_parts mp 
            JOIN assets a ON mp.part_id = a.id 
            WHERE mp.maintenance_id = ?
        `, [record.id]);

        record.parts = parts;
        res.json(record);
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

// Create Maintenance Record
router.post('/assets/:asset_id/maintenance', async (req, res) => {
    const { maintenance_date, type, content, images, parts } = req.body; // parts: [{ part_id, quantity }]
    const { asset_id } = req.params;

    const connection = await db.getConnection();

    try {
        await connection.beginTransaction();

        const sql = `
            INSERT INTO maintenance_history (asset_id, maintenance_date, type, content, images)
            VALUES (?, ?, ?, ?, ?)
        `;
        const [result] = await connection.query(sql, [asset_id, maintenance_date, type, content, JSON.stringify(images || [])]);
        const maintenanceId = result.insertId;

        if (parts && Array.isArray(parts) && parts.length > 0) {
            for (const part of parts) {
                // 1. Deduct quantity from assets
                await connection.query('UPDATE assets SET quantity = quantity - ? WHERE id = ?', [part.quantity, part.part_id]);

                // 2. Add to maintenance_parts
                await connection.query(
                    'INSERT INTO maintenance_parts (maintenance_id, part_id, quantity) VALUES (?, ?, ?)',
                    [maintenanceId, part.part_id, part.quantity]
                );
            }
        }

        await connection.commit();
        res.status(201).json({ message: 'Maintenance record created', id: maintenanceId });
    } catch (err) {
        await connection.rollback();
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    } finally {
        connection.release();
    }
});

// Update Maintenance Record
router.put('/maintenance/:id', async (req, res) => {
    const { maintenance_date, type, content, images, parts } = req.body;
    const maintenanceId = req.params.id;

    const connection = await db.getConnection();

    try {
        await connection.beginTransaction();

        // 1. Update basic info
        const sql = `
            UPDATE maintenance_history 
            SET maintenance_date=?, type=?, content=?, images=?
            WHERE id=?
        `;
        const [result] = await connection.query(sql, [maintenance_date, type, content, JSON.stringify(images || []), maintenanceId]);

        if (result.affectedRows === 0) {
            await connection.rollback();
            return res.status(404).json({ error: 'Maintenance record not found' });
        }

        // 2. Handle Parts Update (Restore old -> Apply new)
        if (parts) {
            // Get existing parts to restore stock
            const [existingParts] = await connection.query('SELECT * FROM maintenance_parts WHERE maintenance_id = ?', [maintenanceId]);

            for (const part of existingParts) {
                await connection.query('UPDATE assets SET quantity = quantity + ? WHERE id = ?', [part.quantity, part.part_id]);
            }

            // Remove existing links
            await connection.query('DELETE FROM maintenance_parts WHERE maintenance_id = ?', [maintenanceId]);

            // Add new parts and deduct stock
            if (Array.isArray(parts) && parts.length > 0) {
                for (const part of parts) {
                    await connection.query('UPDATE assets SET quantity = quantity - ? WHERE id = ?', [part.quantity, part.part_id]);
                    await connection.query(
                        'INSERT INTO maintenance_parts (maintenance_id, part_id, quantity) VALUES (?, ?, ?)',
                        [maintenanceId, part.part_id, part.quantity]
                    );
                }
            }
        }

        await connection.commit();
        res.json({ message: 'Maintenance record updated' });
    } catch (err) {
        await connection.rollback();
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    } finally {
        connection.release();
    }
});

// Delete Maintenance Record
router.delete('/maintenance/:id', async (req, res) => {
    const connection = await db.getConnection();

    try {
        await connection.beginTransaction();

        // 1. Restore stock for used parts
        const [usedParts] = await connection.query('SELECT * FROM maintenance_parts WHERE maintenance_id = ?', [req.params.id]);
        for (const part of usedParts) {
            await connection.query('UPDATE assets SET quantity = quantity + ? WHERE id = ?', [part.quantity, part.part_id]);
        }

        // 2. Delete record (Cascading delete will remove maintenance_parts rows, but we manually restored stock first)
        const [result] = await connection.query('DELETE FROM maintenance_history WHERE id = ?', [req.params.id]);

        if (result.affectedRows === 0) {
            await connection.rollback();
            return res.status(404).json({ error: 'Maintenance record not found' });
        }

        await connection.commit();
        res.json({ message: 'Maintenance record deleted' });
    } catch (err) {
        await connection.rollback();
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    } finally {
        connection.release();
    }
});

// ==========================================
// 3. Manuals
// ==========================================

// Get Manuals for an Asset
router.get('/assets/:asset_id/manuals', async (req, res) => {
    try {
        const [rows] = await db.query('SELECT * FROM asset_manuals WHERE asset_id = ? ORDER BY created_at DESC', [req.params.asset_id]);
        res.json(rows);
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

// Add Manual to Asset
router.post('/assets/:asset_id/manuals', async (req, res) => {
    const { file_name, file_url } = req.body;
    const { asset_id } = req.params;

    try {
        const sql = `INSERT INTO asset_manuals (asset_id, file_name, file_url) VALUES (?, ?, ?)`;
        const [result] = await db.query(sql, [asset_id, file_name, file_url]);
        res.status(201).json({ message: 'Manual added', id: result.insertId });
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

// Delete Manual
router.delete('/manuals/:id', async (req, res) => {
    try {
        const [result] = await db.query('DELETE FROM asset_manuals WHERE id = ?', [req.params.id]);
        if (result.affectedRows === 0) return res.status(404).json({ error: 'Manual not found' });
        res.json({ message: 'Manual deleted' });
    } catch (err) {
        console.error(err);
        res.status(500).json({ error: 'Database error' });
    }
});

module.exports = router;